From David Snokes (by way of Randy Isaac):
"But I can't think of any cases in which a history of the origins, i.e.
a theory of a specific path of changes, was used to generate useful
predictions."

Cladistic and phylogenetic methods can make pretty useful predictions
about the relationships between groups of organisms. They can provide
information about divergence times and relatedness. They can also create
testable hypotheses about future discoveries. For example, the
relationships between birds and specific groups of reptiles was once
uncertain but it was clear what sort of evidence would need to be found
to associate birds to any particular group. These intermediates have
since been discovered and tend to map nicely with one of the models
originally hypothesized.

Biology, in general, is pretty tough work, not just evolutionary biology.